Monday, December 11, 2017

Big Cats Have A Common Ancestor 4.5 Million Years Ago

Extant big cats (i.e. lions, tigers, jaguars, leopards and snow leopards) have a common ancestor just 4.5 million years ago, with some branches related more recently (comparable to the depth of hominin diversification). Domestic cats have a common ancestor with big cats about 12 million years ago (comparable to the chimpanzee-hominin divide).

Friday, December 8, 2017

Australian Aboriginal Myth Describes Variable Brightness Stars

Did you know that a few stars that are visible in the night sky vary in brightness over time, in time frames and magnitude of brightness variability that differ from star to star?

Modern astronomers do and ancient Egyptian astronomers did, but in Western European astronomy this wasn't discovered until a few years before the dawn of the 18th century CE, and many ordinary people today don't know this fact. But, Australian aborigines were well aware of it and embedded it in their mythology.
[N]ew research, recently published in The Australian Journal of Anthropology, reveals that Aboriginal oral traditions describe the variable nature of three red-giant stars: Betelgeuse, Aldebaran and Antares.
From here.

The myths not only embed the variable stars in the myths about the constellations that are home to them, but also recount the relative frequency with which their magnitude varies.

Thursday, December 7, 2017

More Data Narrows Primordial Black Hole Dark Matter Parameter Space

Black hole merger events detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) have revived dark matter models based on primordial black holes (PBH) or other massive compact halo objects (MACHO). This macroscopic dark matter paradigm can be distinguished from particle physics models through their gravitational lensing predictions: compact objects cause most lines of sight to be demagnified relative to the mean, with a long tail of higher magnifications. We test the PBH model using the lack of lensing signatures on type Ia supernovae (SNe), modeling the effects of large scale structure, allowing for a non-gaussian model for the intrinsic SNe luminosity distribution and addressing potential systematic errors. Using current JLA (Union) SNe data, we derive bounds ΩPBH/ΩM<0.346(0.405) at 95% confidence, ruling out the hypothesis of MACHO/PBH comprising the totality of the dark matter at 5.01σ(4.28σ) significance. The finite size of SNe limits the validity of the results to MPBH≳0.01M⊙, fully covering the black hole mergers detected by LIGO and closing that previously open PBH mass range.
Miguel Zumalacarregui and Uros Seljak,"No LIGO MACHO: Primordial Black Holes, Dark Matter and Gravitational Lensing of Type Ia Supernovae"(December 7, 2017).

The limiting minimal size of PBH covered by the exclusion, 0.01M⊙, is equivalent to about ten times the mass of Jupiter (which implies an event horizon of the Primordial Black Hole with a radius of approximately 28 meters, which would fit comfortably within a baseball field).

This is notable, because it makes previous MACHO/PBH exclusions more robust, but the sweet spot for MACHO dark matter was already limited to PBH objects with a mass on the order of the Moon (many hundreds of times less than the mass of Jupiter), and a event horizon radius on the order of millimeters.

Personal Attacks In The Comments Are Strictly Forbidden Here.

This is a warning.

Many blogs in the areas of anthropology and/or physics tolerate some ad hominem (i.e. personal) attacks on other people leaving comments in the comments at their blog, or even make ad hominem attacks in their own posts.

Ad hominem attacks in the comment are completely unacceptable at this blog, and they will be made in original posts here only in very exceptional circumstances.

I am quite willing to tolerate non-mainstream theories and personal conjectures in the comments. And, other commentators are welcome to criticize those theories and conjectures in other comments. But, ad hominem attacks on other people making comments, whether or not they are justified (and sometimes they are), are not permitted here for any reason. 

This is a forum in which a minimum standard civility is imposed.

If you have a criticism of something that someone else has said, you need to figure out how to say that without making it personal (and without making it a racial or ethnic slur or making your point in any otherwise offensive manner).

Northern Chinese Ancient DNA

There is population genetic continuity in Northern China near where the Han Dynasty originated, back to the early Bronze Age (ca. 2000 BCE) according to the ancient DNA that could be extracted from sixty individuals buried a cemetery from that time period. 

Friday, December 1, 2017

Some Southern Central Asians Have About 50% Steppe Ancestry

Davidski at Eurogenes discusses some Southern Central Asian populations in a recent post. This post expands on his rather raw genetic analysis to put his conclusions in historical and anthropological and linguistic context.


Pamiri children via Wipiedia. There are about 350,000 Pamiris in their region, 
who are mostly Shia Muslims


A map showing where Pamiri people live from the same Wikipedia page. 
This region called Badakhshan, is divided between Tajikistan in the north 
and Afghanistan and Pakistan in the south and China's Xinjiang to the west.

Pamiri Tajik Genetics

Davidski demonstrates with convincing autosomal and uniparental genetic evidence that 50% or more of their gene pool is derived from the Pontic Caspian Steppe in Europe (i.e. basically modern Ukraine) with the balance mostly from Iranian farmers and about 8% directly from East Asians. This is consistent with their phenotype, but contrary to the oral history of the origins of their people.
Several South Central Asian populations have a reputation for producing individuals who look surprisingly European, even the lighter shade sort of European from Eastern and Northern Europe. This is especially true of the Pamiri Tajiks, and it's unlikely to be a coincidence, because these people probably do harbor a lot of ancient Eastern European ancestry. 
My own estimates, using various ancestry modeling methods, suggest that Pamiri Tajiks derive ~50% of their genome-wide genetic ancestry from populations closely related to, and probably derived from, Eneolithic/Early Bronze Age pastoralists from the Pontic-Caspian steppe of Eastern Europe, such as the Sredny Stog and Yamnaya peoples.
In his autosomal genetic model he is "using the mostly Yamnaya-derived Iron Age Sarmatians from Pokrovka, Russia, in far Eastern Europe, to illustrate the point. Note that Sarmatians were East Iranic-speakers, which is what Tajiks are."
Many South Central Asian groups, and especially Indo-European-speakers, like the Tajiks, show moderate to high frequencies of two Y-chromosome haplogroups typical of Bronze Age Eastern Europeans: R1a-M417 and R1b-M269. This is old news to the regular visitors here and its implications are obvious, so if you still think that these haplogroups expanded from South Central Asia to Eastern Europe, rather than the other way around, then please update yourself (for some pointers, see here and here). 
And now, courtesy of Peng et al. 2017, we also have a much better understanding of ancient European maternal input into the gene pool of Pamiri groups (see here). The paper doesn't specifically cover the topic of European admixture in South Central Asia, but it nevertheless demonstrates it unequivocally.
In Peng (2017), many mtDNA lineages are: 
shared between Europeans and Central and South Asians; quite a few of these lineages are rooted in Eastern Europe, as shown by both modern-day and ancient DNA, so they strongly imply gene flow, and indeed considerable maternal gene flow, from Eastern Europe deep into Asia. Worthy of note are the lineages belonging to such relatively young (likely post-Neolithic) haplogroups as U5a1a1, U5a1d2b, U5a2a1, and U5b2a1, all of which have already been found in ancient remains from the Pontic-Caspian steppe.
The History of the Pamiri People

The Badakhshan region has had a Silk Road trading based economy attested to with archaeological evidence dating to before 4000 BCE. 

The legendary historical origin story of the Pamiri people, or at least the homegrown dynasty of rulers of Badakhshan, traces the dynasty's origins to the reign of Alexander the Great in the 4th century BCE, although no linguistic or genetic or cultural evidence supports this Iron Age legendary Hellenic history. But, it isn't impossible as the Eastern part of Alexander the Great's empire was a conquered Persian population which may not have involved many Greek and Anatolian migrants below the highest levels of the ruling class and soldiers who did not relocate permanently. It is one of several historical instances where conquerers adopted to a great extent the sophisticated culture of the land they conquered.

Ethnically Persian, local poet and religious scholar Nasir Khusraw led the conversion of the ancestors of the modern Pamiri people to Shia Islam in the 11th century CE.

The kingdom of Badakhshan is historically well attested and flourished from the 15th century CE to 1641 CE, and is mentioned in the Marco Polo story (whose historical accuracy is admittedly sometimes questionable). For the next two centuries, until 1839 CE, the region alternated between conquering outsider Emirs and Khanates, and home grown princes. After that British, Russian and Chinese colonial powers had their way with various parts of the region in succession and not always peacefully. Ultimately today, the region ended up split between Afghanistan and Pakistan (the successors to the British colonial rulers), Tajikistan (successor to Russian and then Soviet colonial rulers), and an autonomous region on the far western frontier of China.

Analysis

At a minimum, Alexander the Great's Iron Age empire, while it may have been one important source of the Iranian Neolithic ancestry of the Pamiri people, which has significant Indo-Iranian steppe admixture itself from sometime in the time frame from ca. 2500 BCE to 1500 BCE or so, was almost surely not the primary source of the substantial and distinctively steppe ancestry found in the Pamiri people relative to Iron Age Iranians.  And the Pamiri apparently also also show little South Asian proper genetic admixture, either in their whole genomes or in their uniparental haplogroups.

This suggests that in the Bronze Age, East Iranian steppe people may have mostly replaced the previous population that had traded there for 1500 to 2000 years or so when these Indo-Europeans arrived.

Part of what makes the ancestry of the Pamiris interesting is that that they have not just autosomal genetic and mtDNA similarity to the Yamnaya people of Ukraine the way the Corded Ware people did, but also significant amounts of Y-DNA R1b-M269 associated with the Southern Steppe, in addition to Y-DNA R1a-M417, associated with the Northern Steppe (which was the predominant Y-DNA haplogroup among both Corded Ware people and people with Indo-Aryan ancestry in South Asia).

Indeed, the fact that the two Y-DNA haplogroups are mixed here, unlike nearby regions adjacent to the steppe, suggests a plausible two step migration, with Y-DNA R1b Yamnaya people forming the first wave that cleared away older populations of the region, and Indo-Iranians (who were predominantly Y-DNA R1a) forming a second wave, perhaps not that many centuries afterwards, who gave the Pamiris their East Iranian language, Y-DNA R1a and an additional dollop of steppe autosomal genetics and steppe mtDNA.

The Y-DNA R1b Yamnaya people, while similar in autosomal genetics and mtDNA to steppe people further north with mostly Y-DNA R1a, whom we can characterize much better linguistically, are almost surely ancestral to Western and Northern European populations where Y-DNA R1b-M269 is predominant. But, the story of their long westward journey and the near disappearance of Y-DNA R1b-M269 men from the steppe they originally inhabited before the Indo-Iranian and Corded Ware expansions as demonstrated by a stark transition in Y-DNA types in ancient DNA in their own homeland is much more of a mystery. 

The linguistic connections between their language(s) the languages spoken in the parts of Europe and Asia where their descendants are now most common is also more obscure. It would be plausible for them to have been linguistically Indo-European, but it isn't a foregone conclusion either, because anthropological and linguistic evidence suggests that the Celtic languages which are the oldest attested languages of the regions where their descendants settled have far to little time depth (1300 BCE or so at most) to have arrived at the same time that the descendants of the Yamnaya people arrived in Western and Northern Europe (ca. 2500 BCE) a dozen centuries earlier.

The Pamiri people are testimony to the fact that the collapsing Yamnaya people had spread to the East on the Silk Road as well as to the West, before or in connection with their collapse.

We don't know if the Y-DNA R1b in the Pamiri is a relict population of a formerly greater Yamnaya range or if it arrives as part of an exodus from Ukraine. But, the fact that they speak an Indo-Iranian language associated with Y-DNA R1a steppe people, denies us much insight in the linguistic character of the Y-DNA R1b steppe people who preceded them, unless substrate influences can be discerned in their East Iranian languages that are not shared by predominantly Y-DNA R1a Indo-Iranian populations.

It would be particularly notable as we try to reconstruct Yamnaya linguistics, if substrate influences found in the Pamiris languages were also shared by Indo-European languages in the Balkans were there is also a mix of Y-DNA R1a and R1b, and in Celtic languages, but was absent in other Balto-Slavic languages and other Indo-Iranian languages. But, those are very fragile ties to establish and doing so is more linguistic art than linguistic science. Alas, in the case of the Pamiris, their historic role as Silk Road traders makes it particularly hard to distinguish substrate influences in their languages from loan words picked up from travelers and fellow Silk Road merchants.

Tuesday, November 28, 2017

The Middle East Really Has Been In The Middle

Over millennia, the Middle East has genuinely been in the geographic middle of many important element of the history of humanity, even though the terminology is a relic of an Anglo-centric British colonial view of the world.

The Upper Paleolithic Middle East


In the autosomal genetic ancestry component analysis above, at K=2, the dark blue represents Eurasian ancestry and the light blue represents African ancestry, with populations including Ethiopians, Arabs and Nubians (geographically in Sudan) being the populations most admixed between the two components (from Dobon, et al. (2015)).

Of course, the biggest divide in modern human genetics, the populations you get if you cluster modern humans into a first break into just two populations, is between Africans and non-Africans, with virtually all non-African ancestry leaving the African continent via the Middle East.

The two non-African mtDNA macro-haplogroups in modern humans, M and N, are branches of African mtDNA haplogroup L3. And, mtDNA haplogroups M and N probably became distinct from mtDNA L3 in or near the Middle East around the dawn of the Upper Paleolithic era (with a most recent common ancestor ca. 50,000 to 70,000 years ago, although archaeological evidence points to a modern human presence in the region ca. 100,000 to 125,000 years ago).


Modern Distributions of mtDNA M1 (left) and U6 (right) from [1].

Tens of thousands of years later in middle of the Upper Paleolithic era, at roughly the same time, two mtDNA haplogroups, M1 and U6, back migrate to what is now the Afro-Asiatic linguistic region of Africa.

One of these, mtDNA haplogroup M1, probably arrives in Africa from the Middle East.[1] The most recent common ancestor of the M1 haplogroup as a whole is about 29,000 years ago. "Both M1b and M1a have close coalescent ages around the LGM: ~20 and ~21 KYA respectively."[1] The M1b clade is more North African, while the M1a clade is more East African.

According to a leading paper on the topic, Secher (2103), mtDNA haplogroup U6 probably arriving from the Strait of Gibraltar from Iberia around 26,000 years ago (about 9,000 years after the mutation that defines mtDNA U6 occurred). Individuals with mtDNA U6 are found in ancient DNA in Morocco from 12,000 years ago.[2]

The Holocene Middle East

There were multiple waves of gene exchange between West Eurasia and Africa during the Holocene era, although it isn't alway easy to be definitive about when during the Holocene particular waves of migration took place.

Africa to West Eurasia

African genetics reach West Eurasia from Iberia, Italy and the Middle East, but in pre-modern times the impact on the Middle East was greater. 

On the Y-DNA side, sister branches of Y-DNA haplogroup E originating in African arrived mostly from Iberia and the Middle East (and on from there to Greece and the Balkans), respectively, probably sometime in the Holocene, although there is considerable lack of clarity regarding when this happened.

West Eurasia to Africa

West Eurasian genetic impacts on Africa, in turn, are mostly from Iberia and the Middle East. But, the Iberian impacts are predominantly Northwest African in territory that was historically Berber language speaking, while almost all West Eurasian genetic impacts on the rest of Africa flow through the Middle East.

One wave of Neolithic migration was of people genetically similar to early Anatolian and/or Levantine farmers and admixed individuals in East Africa probably carried this ancestry with them from there to Southern Africa all of the way to the Khosian people prior to the Bantu expansion.

This may have also been the time at which West Eurasian Y-DNA haplogroup T-M70 (formerly known as K2-M70) reached Africa.[3] While mutation rate based "expansion estimates in Egypt (17.5–13.7 ky) are consistent with an early African diaspora" during the Mesolithic era before the Neolithic revolution (ca. 8,000 years ago in Egypt), and the dispersal of Y-DNA haplogroup T-M70 in Africa is not strongly correlated with other West Eurasian Y-DNA haplogroups in the region such as Y-DNA haplogroups G-M201, J-12f2, and R1-M173. But, mutation rate based dating is not an exact science (and was even less so in 2004 when [3] was published), and circumstantial evidence and archaeology tends to favor a first wave Egyptian Neolithic for Y-DNA haplogroup T-M70 in Africa. In any case, genetic evidence points to a Levantine rather than a Horn of Africa migration route of Y-DNA haplogroup T-M70 to Africa.

On the Y-DNA side, Y-DNA haplogroup R1b-V88 probably reached Africa through the Middle East in the mid-Holocene.[4]

Probably in the Bronze Age, there was a major migration from Arabia to Ethiopia which gave rise to the modern Ethio-Semitic languages and left a significant, male biased, genetic trace as well:
[C]ontemporary Ethiosemitic languages of Africa reflect a single introduction of early Ethiosemitic from southern Arabia approximately 2800 years ago", and that this single introduction of Ethiosemitic underwent "rapid diversification" within Eritrea and Ethiopia.
from the Wikipedia link above citing [5]. 

The Neolithic Middle East





The region we call the "Middle East" is where the two main strands of the Neolithic diverge from each other as shown in the chart above.

It is unsurprising the origin of the Fertile Crescent Neolithic revolution would hold such a focal spot. But, the great genetic distance and stark genetic segregation between the adjacent Anatolian and Iranian populations whose domesticates blended with each other to form a single Fertile Crescent Neolithic technological package is surprising.

The Bronze Age Middle East



The Middle East is also the place, in the Bronze Age, where the boundary between Indo-European languages (Greek, Hittite, Sanskrit in the Mittani elites, and possibly Armenian whose origins are obscure), Afro-Asiatic (Akkadian, Phoenician, Hebrew, South Arabian languages, Coptic) and the various ergative languages spoken by people with "Iranian farmer" ancestry (e.g. Sumerian, Elamite, Hurrian, and the Caucasian languages) were spoken.

The Iron Age

The Iron Age Middle East is the proximate source of the three Abrahamic religions: Judaism, Christianity, and Islam. It also marks the approximate boundary between these Abrahamic religions and the religions generally known as "Eastern Religions" by Anglophones until the expansion of Islam after the fall of the Roman Empire pushes that boundary eastward to India and beyond.

Judaism

Judaism claims roots in Bronze Age Egypt, but by the Torah's account in the Hebrew Bible books of Genesis and Exodus, this religion was still in a formative stage and limited to a dozen nomadic tribes of former slaves wandering in the wilderness of the Sinai until the Jewish people established a confederacy of tribes that was in due course united into a kingdom in the Southern Levant around the time of Bronze Age collapse or early Iron Age.

This theocratic kingdom evolved over a period of centuries, interrupted by political schism, more than one period of exile of substantial numbers of members of the faith to Babylon (i.e. Iraq), and Roman conquest, culminating in the end of Temple Judaism when the leading Jewish temple was destroyed in 70 CE by the Romans, giving rise to the Jewish diaspora and the emergence of Rabbinic Judaism. Towards the end of the pre-Rabbinic Judaism period, towards the tail end of the period in which the Hebrew Bible is set, Zoroastrian influences from Persia begin to significantly influence some sects of Judaism.

In the Jewish diaspora, small communities of Jews end up in Yemen, Africa, India and Spain, but the largest portion of modern Jews, the Ashkenazi Jews, appears to originate from a community of Jews from Italy at the heart of the Western Roman Empire, who subsequently migrate to Eastern Europe, experiencing an extreme population bottleneck around the time of the Christian Crusades, although the location of that bottleneck is hard to discern. Everywhere that Jews migrated, local populations of Jews had substantial, female dominated introgression from local populations mostly in the early years of the formation of those populations before endogamy took hold.

Christianity

Christianity's origins are as a sect within Judaism commencing ca. 30 CE, shortly before the demise of Temple Judaism. This sect of Judaism shows notable influences from both several Greco-Roman pagan cults and from Zoroastrianism, although it incorporates the Hebrew Bible into its canon. The branch of this sect adopted by self-identified Jews was one of several Messianic Jewish sects that rose and fell in the final century or so of Temple Judaism.

But, unlike other post-Temple Judaism sects of Judaism, Christianity evangelized to pagan gentiles, an effort initially spearheaded by Saint Paul, with the tacit, but uncomfortable support of Saint Peter, who according to Christian tradition was the titular leader of all Christians after the crucifixion of Jesus. After three centuries of rapid growth and schism, the faith finally consolidated around the Christian sect ancestral to the Roman Catholic and Eastern Orthodox Churches, whose final consolidation and path to becoming the official state religion of the Roman Empire was pushed along by Roman Emperor Constantine ca. 325 CE (the Council of Nicaea). Between then and the fall, first of the Western Roman Empire and much later the Byzantine Empire as the Eastern Roman Empire came to be known, institutional Christianity became established throughout Roman Europe, the Middle East, and North Africa and persisted even after the respective Western and Eastern empires fell. Islam would sweep away Christianity in the Middle East and North Africa and into Iberia, but Christianity would eventually become the predominant religion of Europe and would expand through missionary efforts and colonial rule elsewhere in the world when the Middle Ages end.

Islam




The Umayyad Calphate at its greatest extent per Wikipedia.

From Islam's inception ca. 632 CE through the Umayyad Caliphate through 750 CE, it expanded from the religion of a few Arabian nomads to one that was predominant from Spain across North Africa, through all of the Middle East and West Asia except Anatolia, and into the Western part of South Asia, reaching then or soon after into Indonesia and to the South to Zanzibar off the coast of what is now Tanzania.

The requirement that adherents who were able make a pilgrimage to Mecca at least once in their life cemented as a matter of doctrine, the centrality of the Middle East in the Islamic world. 

End Notes

[1] Pennarun E, et al., "Divorcing the Late Upper Palaeolithic demographic histories of mtDNA haplogroups M1 and U6 in Africa." 12 BMC Evol Biol. 234 (2012).

[2] Kéfi R, et al., "Diversité mitochondriale de la population de Taforalt (12.000 ans bp - Maroc): une approche génétique à l'étude du peuplement de l'Afrique du Nord." 43(1) Anthropologie 1-11 (2005).

[3] Luis JR, et al., "The Levant versus the Horn of Africa: evidence for bidirectional corridors of human migrations." 74(3) Am J Hum Genet. 532-544 (2004).

[4] Cruciani F, et al., "Human Y chromosome haplogroup R-V88: a paternal genetic record of early mid Holocene trans-Saharan connections and the spread of Chadic languages." 18(7) Eur J Hum Genet. 800-807 (2010).

[5] Andrew Kitchen, "Bayesian phylogenetic analysis of Semitic languages identifies an Early Bronze Age origin of Semitic in the Near East" 276 Proceedings of the Royal Society B (2009).

Musings On Missing Fundamental Particle Possibilities And What Their Absence Might Mean

Disclaimer. This post is made up of more or less numerological speculative conjectures and musings and really has not solid grounding in proven physics or the academic literature. If you are looking for that move along.

How Many Interchangeable Parts Are There?


In the Standard Model of Particle Physics there are 90 kinds of fundamental fermions of spin 1/2 and 13 kinds of fundamental bosons (8 gluons of spin-1, W+, W-, Z and the photon each of spin-1, and one of spin-0, the Higgs boson) for a total of 103 interchangeable parts that differ from each other only in location and momentum, which are continuous parameters related via the uncertainty principle.

A minimal theory of everything must add at least one boson, a graviton of spin-2 bringing the total types of interchangeable parts in the universe to 104.

Vector bosons are also distinguished from each other by helicity (left, right or neutral for a spin-1 particle if massive, but only left or right if massless) which is a discrete although less fundamental trait. I don't think that a spin-0 Higgs boson can have helicity other than zero (another discussion without a really clean answer is here). Considering helicity, there are 28 kinds of bosons (16 gluons, 2 photons, 6 Ws, 3 Zs and 1 Higgs), rather than 13, and the grand total would be 118 without the graviton.

A graviton (if it were massive) could naively have up to five helicity states (since it is spin-2 rather than spin-1), so with the graviton, there would be 123 kinds of interchangable parts that differ from each other only in location and momentum which are continuous parameters related via the uncertainty principle. But, there are arguments that in light of the fact that it is massless (assuming it is massless) and that general relativity is honored, that it should actually only have two states +/- 2 (see also here) or three states, 0 and +/- 2 (in variants from GR), imply a total of 120 or 121 kinds of interchangeable parts with 120 being the most conventional answer.

Otherwise, each of these interchangeable parts is perfectly identical to every other interchangeable part of the same part (subject also to quantum entanglement networks which make some particles distinct from others).

Thus, in the Standard Model extended minimally to include graviton based gravity, any particle can be fully described (except for entanglement links to other particles) by a discrete valued scalar type code with 120-123 possible discrete values, a location vector (in four dimensions) and a momentum vector (in four dimensions). In the Standard Model alone, the vectors are the same but the discrete valued scalar type code would have just 118 possible discrete values. And, everything in the universe is made up of particles (gravitons eliminate a physical medium of space-time that can be warped and have reality apart from gravitons). Put another way, every particle in the universe which makes up everything in the universe can be fully described with nine real numbers in this hypothetical minimal theory of everything (one discrete valued real number and four complex numbers would also get the job done).

Incidentally, the number of particles in the Universe is on the order of 1090, so the number of distinct real numbers numbers necessary to fully describe the universe at any given point in time (recognizing that the definition of a given point in time in the universe is definitionally problematic and ignoring quantum entanglement) is about 1091. It isn't terribly straightforward to quantify exactly how much quantum entanglement complicates this analysis, although it definitely makes it vastly more complex.

Standard Model Fermions

Quarks and Anti-Quarks come in three generations and four possible electromagnetic charges and two possible parities, and for each of the possible types of electromagnetic charges three possible color charges for a total of 72 possibilities. 

Half of them interact via W and Z bosons, gluons and photons:

upLR, upLG, upLB, charmLR, charmLG, charmLB, topLR, topLG, topLB;

antiupRr, antiupRg, antiupRb, anticharmRr, anticharmRg, anticharmRb, antitopRr, antitopRg, antitopRb;

downLR, downLG, downLB, strangeLR, strangeLG, strangeLB, bottomLR, bottomLG, bottomLB;

antidownRr, antidownRb, antidownRb, antistrangeRr, antistrangeRg, anitstrangeRb, antibottomRr, antibottomRg, antibottomRb;

Half of them interact via gluons and photons but not W and Z bosons:

upRR, upRG, upRB, charmRR, charmRG, charmRB, topRR, topRG, topRB;

antiupLr, antiupLg, antiupLb, anticharmLr, anticharmLg, anticharmLb, antitopLr, antitopLg, antitopLb;

downRR, downRG, downRB, strangeRR, strangeRG, strangeRB, bottomRR, bottomRG, bottomRB;

antidownLr, antidownLb, antidownLb, antistrangeLr, antistrangeLg, anitstrangeLb, antibottomLr, antibottomLg, antibottomLb.

Charged Leptons and Anti-Charged Leptons come in three generations and two possible electromagnetic charges and two possible parities for a total of 12 possibilities.

Half of them interact via W and Z bosons and photons:

electronL, muonL, tauL, antielectronR, antimuonR, antitauR;

Half of them interact via photons but not W and Z bosons:

electronR, muonR, tauR, antielectronL, antimuonL, antitauL.

Neutrinos come in three generations and two possible parties for a total 6 possibilities:

They interact via W and Z bosons

neutrinoL, muonneutrinoL, tauneutrinoL;

antineutrinoR, antimuonneutrinoR, antitauneutrinoR.

It is notable that as far as we know, there is no evidence that a left handed neutrino (of any generation) can oscillate with a right handed antineutrino (of any generation). 

But, neutrino oscillation between mass eigenstates is a phenomena not seen in any other kind of Standard Model particle, although there are some similar phenomena.

What's Missing?

There are three Standard Model forces mediated by gluons (strong), W and Z bosons (weak) and photons (electromagnetic), respectively.

* The Standard Model has types of particles that interact via all three of these forces:

36 kinds of fermions interact via gluons, W and Z bosons and photons.

* The Standard Model has types of particles that interact via two of the three possible combinations of two of these forces:

36 kinds of fermions interact via gluons and photons
6 kinds of fermions interact via W and Z bosons and photons

* The Standard Model has types of particles that interact only via each one of these forces:

6 kinds of fermions interact via photons only.
6 kinds of fermions interact via W and Z bosons only
8 kinds of bosons (gluons) interact via gluons only 

* The Standard Model has one type of particle that doesn't interact with gluons or photons or Z bosons, and doesn't interact via the weak force with W bosons.

Like right handed charged leptons, photons only interact with charged particles (i.e. quarks and charged leptons and W bosons) via electromagnetism, but photons don't interact with other photons since they have no color charge or electromagnetic charge or weak force charge (yes, I know that this isn't the proper terminology) themselves.

* The Standard Model doe not have any type of particle that interacts via gluons and W and Z bosons, but not photons. A hypothetical particle of this type would be a "neutral left handed quark" or a "neutral right handed antiquark".

To fit the pattern would have to be a massive fermion with three generations. Neutral left handed quarks would have color charges R, G or B; neutral right handed antiquarks would have color charges r, g or b. 

There would also be neutral right handed quarks and neutral left handed antiquarks that would acquire mass by parity oscillation like charged fermions do with color charges R, G and B and r, g and b respectively. Indeed the difference between color charge and anticolor charge would make the neutral right handed quarks not degenerate with the neutral right handed antiquarks, and would make the neutral left handed antiquarks not degenerate with the neutral left handed quarks.

My only novel (for me) conjecture of the day, is that the non-existence of neutral quarks and neutral anti-quarks is probably one of the biggest hints about deeper string-like or preon-like structure in the Standard Model.

All hadrons have integer electromagnetic charge (baryons must have a charge of zero, +/- 1, or +/- 2; mesons must have a charge of zero, or +/- 1).

All fundamental bosons also have integer electromagnetic charge (zero or +/- 1).

No quarks have integer charge.

Preon Theories?

The most obvious possibility would be that color charged preons are the deep source of electromagnetic charge, in which the color charge would be present but cancelled out, at least in no-zero integer charged fundamental particles.

In this scenario, up-like quarks and antiquarks would contain two color charged preons (with the effective color charge of an up-like quark determined by the color charge type it is missing), down-like quarks and anti-quarks containing one color charged preon, charged leptons containing three color charged preons (one of which color, which would eliminates its need to interact via the strong force which it does only internally). W bosons would likewise have to have three color charged preons (one of each color).

There would be neutrinos containing either no color charged preons or a color charged preon and color charged antipreon, and similarly Z bosons, like neutrinos could either lack color charged preons or have one color charged preon and one color charged antipreon of the same type.

Gluons are already hypothetically a color charged-anticolor charged pair.

Photons could also be a color complete set of preons.

Photons and gluons would lack the "weak force" interaction preon or character (perhaps something parity-like or parity-related), while fundamental fermions including neutrinos, W bosons and Z bosons would all have the "weak force" interaction preon or character. 

It probably makes more sense for neutrinos to have a color charged preon and a color charged antipreon and a weak force core, while Z bosons have a weak force core but no color charged preons. This way, all fermions would have a weak force core and color charged preon combinations.

Worked properly (and the simple naive version I suggested above might not accomplish this) a color charge preon theory could also explain baryon number and lepton number conservation.

* One could also have some sort of knot or string twisting scenario that is functionally equivalent to this preon approach.

Another Observation Regarding Mass and The Weak Force

Every type massive particle in the Standard Model either has weak force interactions via the W and Z boson, or has a parity flipped variant that does. In the case of the quarks, antiquarks, charged fermions, charged antifermions, W boson, Z boson and Higgs boson the source of this mass is an interaction with the Higgs field.

The Standard Model does not resolve the question of the source of the mass of the neutrinos and antineutrinos, but it is notable that they too have weak force interactions via W and Z bosons.

Every type of massless particle in the Standard Model, i.e., the photon and the gluon, does not have weak force interactions. In a minimal theory of everything, the graviton doesn't interact via the weak force either, although gravitons do hypothetically interact with every kind of particle including itself.

Sterile Neutrinos Considered

A hypothetical "sterile neutrino" (i.e. neutrinoR, muonneutrinoR, taunautrinoR, antineutrinoL, antimuonneutrinoL, antitauneutrinoL), per my conjecture would be massless in addition to not interacting via any of the Standard Model forces. Since massless particles can't have distinct generations, a "sterile neutrino" could actually come in only two types: neutrinoR and antineutrinoL.

In a Standard Model with or without gravity, a massless sterile neutrinos are irrelevant and non-existent since they don't interact with anything (although I seem to recall one beyond the Standard Model theory that predicts the existence of massless sterile neutrinos). But, perhaps a massless neutrinoR and antineutrinoL system could be a single Majorana singlet sterile neutrino with Majorana mass not tightly coupled to the fundamental masses of the Standard Model and facilitating a simple dark matter particle. But, this is much less well motivated these days than it used to be because the case for collisionless dark matter of any kind is in such trouble.

But, sterile neutrinos might acquire mass identical to their non-sterile counterparts through oscillations between left and right handed neutrinos, and oscillations between left and right handed antineutrinos, in which case there could be six rather than two versions of them, and they would interact via gravity and hence become dark matter candidates, although then they would be hot dark matter, which again, observational evidence suggests that we don't need.

There is really no experimental motivation, however, that strongly necessitates sterile neutrinos, except that they would make Dirac neutrino mass identical to the other fundamental fermions possible.

The notion of sterile neutrinos that are neither massless nor have masses identical to their non-sterile counterparts of the same generation seems to me to be much less well motivated theoretically, even though right handed neutrinos with masses different than the "fertile" neutrinos of the Standard Model are very popular in beyond the Standard Model physics scenarios.

Gravitinos?

There are fundamental particles with spin-0, spin-1/2, spin-1 and in the hypothetical case of the graviton spin-2. There are no Standard Model fundamental particles with spin-3/2, nor are there any in a minimal theory of everything extension with a spin-2 graviton. 

A spin-3/2 gravitino, as a singlet fermionic dark matter candidate if one needed one (normally found in SUSY theories, but conceivable without SUSY) could theoretically exist and fill this gap. Indeed, it could also conceivably also be a neutral quark with no electromagnetic interactions, or could be a three generation triplet like the other fermions.

Meta

This post brings the posting rate so far this year at this blog to 21 posts per month.

More Dark Matter Phenomena Data Points

The following two papers illustrate observations of dark matter phenomena in circumstances when conventional dark matter explanations don't make sense. These two use the simple MOND toy model, which, admittedly has problems. 

But, they key point is that the data points aren't a good fit for dark matter particle theories, and that modified gravity theories are predictive in circumstances other than the ones in which they were formulated.

This paper is notable because wide binary stars would not be expected to have dark matter halos analogous to those alleged to form galaxies and galactic clusters.
Assuming Newton's gravity and GR to be valid at all scales leads to the dark matter hypothesis as a requirement demanded by the observed dynamics and measured baryonic content at galactic and extragalactic scales. Alternatively, modified gravity scenarios where a change of regime appears at acceleration scales a<a0 have been proposed. This modified regime at a<a0 will generically be characterised by equilibrium velocities which become independent of distance. Here we identify a critical test in this debate and we propose its application to samples of wide binary stars. Since for 1M⊙ systems the acceleration drops below a0 at scales of around 7000 AU, a statistical survey of wide binaries with relative velocities and separations reaching 104 AU and beyond should prove useful to the above debate. We apply the proposed test to the best currently available data. Results show a constant upper limit to the relative velocities in wide binaries which is independent of separation for over three orders of magnitude, in analogy with galactic flat rotation curves in the same a<a0acceleration regime. Our results are suggestive of a breakdown of Kepler's third law beyond a≈a0 scales, in accordance with generic predictions of modified gravity theories designed not to require any dark matter at galactic scales and beyond.
Hernandez et al., "Wide binaries as a critical test for Gravity theories" (2012)  https://arxiv.org/abs/1205.5767

A November 2016 paper by Scarpa, et al., updates this result on wide binaries.

Globular clusters at the fringe of a system are another place where dark matter particles are not expected to be present.
Non-baryonic Dark Matter (DM) appears in galaxies and other cosmic structures when and only when the acceleration of gravity, as computed considering only baryons, goes below a well defined value a0=1.2e-8 cm/s/s. This might indicate a breakdown of Newton's law of gravity (or inertia) below a0, an acceleration smaller than the smallest probed in the solar system. It is therefore important to verify whether Newton's law of gravity holds in this regime of accelerations. In order to do this, one has to study the dynamics of objects that do not contain significant amounts of DM and therefore should follow Newton's prediction for whatever small accelerations. Globular clusters are believed, even by strong supporters of DM, to contain negligible amounts of DM and therefore are ideal for testing Newtonian dynamics in the low acceleration limit. Here, we discuss the status of an ongoing program aimed to do this test. Compared to other studies of globular clsuters, the novelty is that we trace the velocity dispersion profile of globular clusters far enough from the center to probe gravitational accelerations well below a0. In all three clusters studied so far the velocity dispersion is found to remain constant at large radii rather than follow the Keplerian falloff. On average, the flattening occurs at the radius where the cluster internal acceleration of gravity is 1.8+-0.4 x 10^{-8} cm/s/s, fully consistent with MOND predictions.
Scarpa et al., "Globular Clusters as a Test for Gravity in the Weak Acceleration Regime" (2006) https://arxiv.org/abs/astro-ph/0601581

This is also a more recent August 2010 paper and a more recent September 2016 globular cluster paper by some of the same authors.

Monday, November 27, 2017

The Impossible Early Galaxy Problem And Other Cracks In The ΛCDM Model

Another problem with the ΛCDM "standard model of cosmology."
The current hierarchical merging paradigm and ΛCDM predict that the z ∼ 4−8 universe should be a time in which the most massive galaxies are transitioning from their initial halo assembly to the later baryonic evolution seen in star-forming galaxies and quasars. However, no evidence of this transition has been found in many high redshift galaxy surveys including CFHTLS, CANDELS and SPLASH, the first studies to probe the high-mass end at these redshifts. Indeed, if halo mass to stellar mass ratios estimated at lower-redshift continue to z ∼ 6−8, CANDELS and SPLASH report several orders of magnitude more M ∼ 10^12−13 M⊙ halos than are possible to have formed by those redshifts, implying these massive galaxies formed impossibly early. We consider various systematics in the stellar synthesis models used to estimate physical parameters and possible galaxy formation scenarios in an effort to reconcile observation with theory. Although known uncertainties can greatly reduce the disparity between recent observations and cold dark matter merger simulations, even taking the most conservative view of the observations, there remains considerable tension with current theory.
Charles L. Steinhardt, et al., "The Impossibly Early Galaxy Problem" (June 3, 2015).

Along the same lines (and note that wCDM is not WDM):
We continue to build support for the proposal to use HII galaxies (HIIGx) and giant extragalactic HII regions (GEHR) as standard candles to construct the Hubble diagram at redshifts beyond the current reach of Type Ia supernovae. Using a sample of 25 high-redshift HIIGx, 107 local HIIGx, and 24 GEHR, we confirm that the correlation between the emission-line luminosity and ionized-gas velocity dispersion is a viable luminosity indicator, and use it to test and compare the standard model ΛCDM and the Rh=ct  Universe by optimizing the parameters in each cosmology using a maximization of the likelihood function. For the flat ΛCDM model, the best fit is obtained with Ωm=0.40+0.090.09. 
However, statistical tools, such as the Akaike (AIC), Kullback (KIC) and Bayes (BIC) Information Criteria favor Rh=ct over the standard model with a likelihood of 94.8%98.8% versus only 1.2%5.2%     . For wCDM (the version of ΛCDM with a dark-energy equation of state wdepde/ρde rather than wde=wΛ=1), a statistically acceptable fit is realized with Ωm=0.22+0.160.14 and wde=0.51+0.150.25  which, however, are not fully consistent with their concordance values. In this case, wCDM has two more free parameters than Rh=ct, and is penalized more heavily by these criteria. We find that Rh=ct is strongly favored over wCDM with a likelihood of 92.9%99.6% versus only 0.4%7.1%. The current HIIGx sample is already large enough for the BIC to rule out ΛCDM/wCDM in favor of Rh=ct at a confidence level approaching 3σ.
Jun-Jie Wei, et al., "The HII Galaxy Hubble Diagram Strongly Favors R_h=ct over ΛCDM" (August 6, 2016).